LED application in educational lighting, what should I pay attention to?
2019-04-23

As a solid-state semiconductor light source, LED has been continuously improved in light efficiency and prices have been declining. Compared with traditional light sources, LEDs have many advantages such as small size, adjustable and controllable, long life, etc. LED lighting products have been rapidly developed and widely concerned in many application fields such as classroom lighting.


This article discusses the issue of whether the current classroom lighting can use LED light source in the society, which is discussed and questioned in the society. It aims to introduce the concept and explain the relevant concepts to people.


Controversy over the use of LED light sources in classroom lighting


At present, there are two main disputes about the 'can use LED light source in classroom lighting at this stage'.


1) In the rapid development of LED technology, LED lamps are gradually replacing the mainstream “rare earth trichromatic fluorescent lamps” used in classroom lighting. Does the current national standard for classroom lighting allow and recommend the use of LED light sources?


2) In the context of the increasing quality of lighting products, Blu-ray hazards, stroboscopic and other issues have become a hot topic in society. Does the LED light source have potential safety hazards to the visual health of children during development?


Does the national standard allow classrooms to use LEDs?


The current effective classroom lighting standards include “Standards for Lighting and Lighting in Classrooms of Primary and Secondary Schools” (GB7793-2010), “Design Standards for Primary and Secondary Schools” (GB50099-2011), and “Specifications for Lighting Design of Primary and Secondary Schools and Kindergartens” (DB31/539- 2011) 'Architectural Lighting Design Standards' (GB50034-2013), 'Technical Specifications for Energy-Efficient Certification for Lighting in Primary and Secondary Schools and Kindergarten Classrooms' (CQC 3155-2016), average illuminance and illuminance uniformity of classrooms, average illuminance and illumination of blackboards Uniformity, uniform glare value, color rendering index, light source color temperature, luminaire efficiency and power density are required. These standards are applicable to all types of light sources.


Regardless of whether it is an LED or a conventional light source, the corresponding parameters should meet the requirements of the lighting standards for various indicators when used for classroom lighting.


Due to the development and gradual popularization of LED lighting products, it is necessary to standardize classroom lighting LEDs. At present, China Quality Certification Center (CQC) has released the “Technical Specifications for Energy-saving Certification for Lighting in Primary and Secondary Schools and Kindergarten Classrooms” in 2016. The parameters have been further standardized, and other standards for LED classroom lighting fixtures have yet to be perfected.


LED light source has safety hazards


At present, the efficacy and luminaire efficiency of white LEDs for general lighting have surpassed that of traditional light sources, and can achieve high color rendering and high stability, and can meet the demand for dimming of intelligent lighting. The key to the use of LEDs depends on whether the final luminaire can meet the lighting specifications and related lighting requirements.


For the photobiosafety issue of LED, please refer to the 'General Lighting LED and Blu-ray' white paper jointly released by the International Semiconductor Lighting Alliance, the National Semiconductor Lighting Engineering R&D and Industry Alliance and the China Lighting Society in July 2013. It is clearly stated in the white paper that the correct use of qualified general-purpose white LED products is completely safe for the human eye.


At present, public opinion has many concerns about Blu-ray, but we cannot neglect it for Blu-ray.


On the one hand, blue light is an important component of white light, which not only plays an important role in ensuring color rendering, but also regulates the circadian rhythm. Outdoor daylight can satisfy the function of synchronously regulating the human body's circadian rhythm (or circadian clock), and the indoor exposure of blue light is much less than the dose received by outdoor activities. Blue and cool white light sources can be used to create a suitable light environment to help people get the daily dose of blue light to ensure that their circadian rhythm is coordinated with the natural circadian rhythm.


On the other hand, the “blue light hazard” we usually hear refers to the 400-500 nm blue light band of the light source. If the radiance is too high, the eye may cause photochemical damage to the retina after long-term direct view of the light source. The blue light problem is essentially the combination of radiance, blue light weighting function and time. From the spectral point of view, the blue light ratio of the LED spectrum increases when the color temperature rises, but there is nothing special compared with the blue light of the fluorescent light spectrum. At the same time, the upper limit of the blue light security of the LED is similar to that of a fluorescent lamp.


There is a unified rating specification for blue-light retinal hazards at home and abroad GB/T 20145-2006/IEC62471. LED lamps for daily general lighting belong to level 0 or level 1, which is a safety category.


What should be paid attention to when using LEDs in classrooms?


At present, the use of school classroom lighting LED lights has problems such as brand clutter, uneven quality, unregulated market, lack of regular maintenance, and unsound standards. However, the problem cannot be attributed to the LED light source itself.


Classroom lighting should pay attention to the following issues when using LED products:


First of all, the selected LED products should meet the specification requirements in terms of quality such as light color quality, including meeting safety level requirements, performance requirements, reliability requirements, and environmental protection regulations;


Secondly, the light source and lighting system should be used correctly, including proper lighting design, proper installation, regular inspection and maintenance, etc.


Finally, for all types of light source and lighting system products, photobiosafety testing should be carried out. Even if they are safe and do not require additional warning signs based on the standard, users should avoid long-term direct view of these light sources. Especially in the case of shorter distances.


Source: City Optical Network